Refractory material



Patented June 7 23, 1931 FFHQE "roan nonnn'r Bantam). or STOCKHOLM,swnnmv REFRACTORY MATERIAL Ito Drawing.

Original application med. November 12, .1927, Serial No. 232,947, and inGermany June 4,

1927. Divided. and this application'filed'october 6, 1928. Serial No.310,917.

Thisinvention relates to a fused refractory material having as essentialcompo-. nents oxides of magnesium and aluminum. This application is adivision of my copending application Serial No. 232,947 of 'November12th, 1927. The new product may especially be produced as a slag byreducing oxides or oxide ores in electric furnaces. A typical slag ofthe new kind has for example the following composition:

Per cent Silicic acid 11.2 Aluminum oxide 34.5

' Iron oxide 3.0 1 Titanium oxide 2.0 Manganese oxide 0.4 Chromium oxide21.5 Calcium oxide 3.2 Magnesium oxide 23.6

The relation between the contents in the n slag of magnesium oxide. andaluminum oxide respectively may be varied within very wide limits.However, the magnesium oxide cohtentshould be at least 15% and thealuminum oxide content preferably greater than If no chromium oxide isoccurring, the total content-of oxides of magnesium and aluminumtogether with in certain cases occurring titanium should-at least amountto 75% of the total oxide content of the slag. The content of silicashould be low or less than 15% and suitably; below 12%. The content" ofiron oxides in the slag should be less than 5%. A considerable amount ofchromium oxide has proved to have a very favorable influence upon thechemical resistance of the refractory slag. Said influenceisconsiderable already by 5 to 8% Cr O The best" results, however, areobtained with a chromium oxide content from. about 10 up to aboutpercent. In case of chromium oxide the content of chromium oxidein'excess of 5% counted together with oxides of magnesium and aluminumshould preferably amount to at least 75% of the total oxide content ofthe slag.

p The new product may be obtained in electrio furnace reductionprocesses either by selection of the raw materials for that purpose orby adding slag forming admixtures in form of material containingmagnesium oxide, aluminum oxide or chromium oxide.

The reduction may for instance be utilized in the production of iron orironalloys out of iron ores. I Such-ores contain usually comparativelysmall quantities of magnesium oxide and aluminum oxide but on the otherhand often a considerable content of silicic acid. Most convenient forcarrying out the process is to select ores with low or a comparativelylow silicic .acid content because in such cases. it will be easier toadapt the composition of the slag so that a good highly refractorymaterial can be obtained out of it. If however, it is not possiblebysuitably selecting the raw material to obtain a slag with low silicicacid content special slag forming admixtures are to be used. As v slagforming admixtures in the process, magnesite in a burnt or unburnt stateand bauxite are used with advantage. ore contains a high'percentage ofsilicic acid, the same may, however, be decreased to a percentage lowenough forobtaining a highly refractory material. This may be doneeither by reducing a part of the silicic acid so that iron containingsilicium is obtained, or by adding magnesite or, bauxite with alowcontent of silicic acid, or by adding a larger quantity of suchmaterial that might.

contain a somewhat higher percentage of silicic acid but stillsubstantially less than 15% of the slag forming oxides in the saidadmixtures. It is of advantage to regulate the process in such a waythat the silicic acid content in the slag is less than 12%, while herebybesides a more refractory material, a substantially increased resistanceagainst chemical influences is achieved. For the rest the proportionsbetween iron ore and slag forming ingredients containing MgO or A1 0,may be varied within very wide limits. Even iron ores'containingtitanium may be used in the process. The reduction process is thensuitably so carried out: that all or a part of the titanic acid in {theore goes into the slag as a component.

If the iron into suitable moulds, whether the same has the first withthe such as place be produced in connection production .of chromiumalloys,

may for example be obtained by so adapting the composition of thecharging materials in reduction chromium, chromium steelor otherchromium alloys, for example by adding magnesite Nor bauxite or both,that a desired chromium content is received in the slag- It isespecially suitable tg decrease the total content of silicic acid; andferrous oxide to at the most The content of magnesium 'oxide in the slagmay partly be replaced,-but atthe most to oneifourth, withcalcium'oxi-de. "The highly refractory materials may of course also beproduced by smelting together materials suitable for the purpose. 'Onemay then start either from the simple oxides themselves or from suitableminerals and out of them for example produce a refractory materialholding in accordance with the above statements for the main part oxidesmagnesium and aluminum,-

-- of chromium,

chromium oxide for exampleoccurring in quantities from a few up to andmagnesium oxide from 15% and more. 30' The smelting maybe undertaken intapf ping furnaces. as well as, for example 1n batch processes, infurnaces of the same kind as ordinarily used in the production ofalundum. The received smelt may'be directly cast been obtained inthe forof a slag from any metallurgical or othe reduction process or if thesame has been, brought into molten condition by means 'of'other smeltingro-' low carbon ferrorchromium. y 5 highly refractory product containingC130 processes for producing ferro- 5% of oxide of chromium, not lessthan 75% of oxides of magnesium, aluminum and chromium counted together,and with a content of silica less than 12% and of oxide of iron lessthan5%, characterized by high softening temperature and resistanceagainst chemical erosion. 2. As a new article of manufacture a .fusedrefractory material containing not less vthan 5% of oxide of chromium,not less than F 15% of oxide of magnesium, not less than 75% of oxide ofmagnesium, aluminum and chromium together, and from 5 up to 12% ofsilica.

- v3. A refractory material having as an essential component particlesof a fused re-,

fractor 35% o oxide of chromium, not ,less than 15% of magnesium oxide,not less than 75% of oxides of magneslum, aluminum and chromium; countedtogether, less of silica, less than 5% of iron oxides, and calcium oxidein an amount less than" one fourth of the percentageof magnesium oxide.V 4. A- refractory material having as an esmaterial containing from 5 upto than 12% 25% of oxide of alum1num,'not'lessthan sentialcomponent'particles of a fused refractory material containing not lessthan 5% of oxide of chromium, not less than 75%- of oxides of magnesium,aluminum and,

my hand.

j ROBERT 'HAGLUN D.

' cesses. For this. purpose it is ofadvan age that the total content ofoxides of iron nd silici-um be not -too low.

' 45 Hereby a more fluid slag stone are obtained.

The same Should 1 .-:in such a case not be less than about.5%.-"

and a tight-slag 1 Another way of treating the new refracv tory materialconsists in crushing the cooled mass or for smelt and using it asavstampl- 60 the manufacture of bricks. As inding a cut small quantitiesof claysubstances, sodlum silicate, Sorel cement, suitable hydrates,such as those" of magnesium,

I m1um, or-other binding 55 means may be used.

The new highly refractory. material or the articles an" 'extraor(produced thereof possess besides inary. high refractoryability]aluminum or chroand a 'hig h softening temperature a-great chemical'resistanceq- It is for instance esuse in open hearth fur-' channels and60 pecially'suitable for naces, arches, liningof furnace as material forfurnace bottoms.

Y Iclaim:-

1. As a new article of manufacture afused I 65 refractory materialcontaining not less than of silica and less than 5% of iron ox,-

In testimony whereof have hereunto set

